The users of data processing equipment increasingly find the cloud-based infrastructure-as-a-service, or IaaS, model to be a flexible, easy, and affordable way to access the IT infrastructure they need. By moving servers and applications into logical units referred to as Virtual Data Centers (VDCs), that can be easily deployed with an IaaS provider, these customers are free to build out equipment that exactly fits their requirements at the outset, while having the option to adjust with changing future needs on a “pay as you go” basis. VDCs, like other cloud-based services, bring this promise of scalability to allow expanding servers and applications as business needs grow, without having to spend for unneeded hardware resources in advance. Additional benefits provided by professional level cloud service providers include access to equipment with superior performance, security, disaster recovery, and easy access to information technology consulting services.
Beyond simply moving hardware resources to a remote location accessible in the cloud via a network connection, multiple virtualization technologies provide further abstraction layers within VDCs that makes them attractive. Server virtualization decouples physical hardware from the operating system and other information technology and resources. Server virtualization allows multiple virtual machines with different operating systems and applications to run in isolation side by side on the same physical machine. A virtual machine is a software representation of a physical machine, specifying its own set of virtual hardware resources such as processors, memory, storage, network interfaces, and so forth upon which an operating system and applications are run.